Navegando por Assunto "Climate change"

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Artigo
Modern anthropogenic drought in Central Brazil unprecedented during last 700 years
(2024-02-26) Stríkis, N.M; Buarque, P.F.S.M; Cruz, F.W; et al.
A better understanding of the relative roles of internal climate variability and external contributions, from both natural (solar, volcanic) and anthropogenic greenhouse gas forcing, is important to better project future hydrologic changes. Changes in the evaporative demand play a central role in this context, particularly in tropical areas characterized by high precipitation seasonality, such as the tropical savannah and semi-desertic biomes. Here we present a set of geochemical proxies in speleothems from a well-ventilated cave located in central-eastern Brazil which shows that the evaporative demand is no longer being met by precipitation, leading to a hydrological deficit. A marked change in the hydrologic balance in central-eastern Brazil, caused by a severe warming trend, can be identified, starting in the 1970s. Our findings show that the current aridity has no analog over the last 720 years. A detection and attribution study indicates that this trend is mostly driven by anthropogenic forcing and cannot be explained by natural factors alone. These results reinforce the premise of a severe long-term drought in the subtropics of eastern South America that will likely be further exacerbated in the future given its apparent connection to increased greenhouse gas emissions.
Artigo
Persisting while changing over time: modelling the historical biogeographic of cave crickets (Orthoptera, Grylloidea) in Neotropics
(2023) Castro-Souza, Rodrigo Antônio; Sobral-Souza, Thadeu; Rabelo, Lucas Mendes; Zefa, Edison; Ferreira, Rodrigo Lopes
Using species distribution modelling (SDMs) techniques, we predicted the biogeographic history of crickets commonly found in Neotropical caves as a way to detect potential long-term environmental refuges in South America. Our models were built based on a thorough investigation of existing database regarding the genus Endecous Saussure, 1878 (Ensifera: Phalangopsidae) occurrences. The predictions of their distribution were obtained for two paleoclimate scenarios (LGM — 21 ka and Mid-Holocene — 6 ka), the current climate scenario (0 ka) and one future global warming climate scenario (RCP8.5, 2080–2100). Our findings suggest that in the past, the potential distribution of the crickets was wider, with potential forest corridors connecting different karst areas with caves within their occupancy area. The future prediction indicates a drastic reduction in their spatial distribution with an increased potential for isolation in subterranean ecosystems. Atlantic humid forest patches and caves represent the main environmental refuges for these crickets. Considering the ongoing impacts on surface environments and future climate change, the conservation of caves and karst landscapes has become one of the main strategies for the maintenance of these crickets and all the correlated subterranean communities.
Artigo
Thermal constraints explain and distribution of the climate telict lizard Colobosauroides carvalhoi (Gymnophthalmidae) in the semiarid Caatinga.
(South American Journal of Herptology, 2018) Recoder, Renato Sousa; Magalhães-Júnior, Arnaldo; Rodrigues, Juliana; Pinto, Hugo Bonfim de Arruda; Rodrigues, Miguel Trefaut; Camacho, Agustín
Within the semiarid Caatinga of Brazil, a biome dominated by a xeric arboreal-arbustive vegetation, many lizards are restricted to forest remnants associated with highlands. Although critical for conservation, data to understand the constraints on the distribution of those potential climate relicts are almost nonexistent. Here, we studied aspects of the ecology of the relict forest lizard Colobosauroides carvalhoi (Gymnophthalmidae) in the Caatinga of southern Piauí, northeastern Brazil. We combined data obtained through active sampling with voluntary thermal maximum (VTM) and measurements of environmental temperatures made in different habitats, microhabitats, and seasons to test the prediction that thermal constraints explain the local distribution and abundance of this species. In four field trips, we captured 22 individuals in pitfall traps and 93 in active searches, all in canyon-like valleys covered with semi-deciduous forests. Using plot sampling, we observed that density decreased as distance from rock cliffs increased. Density did not differ among sampling localities but varied among seasons. Field body temperatures were similar to soil temperatures under the leaf litter and lower than air and surface temperatures. Environmental temperatures in forests were lower than the VTM estimated for C. carvalhoi, especially under the leaf litter. Nevertheless, environmental temperatures usually exceeded the VTM at forest borders and in caatingas, in which the species was absent. Our results confirm that C. carvalhoi is spatially constrained to patches of semi-deciduous forests and suggest that its low thermal tolerance likely prevents it from occurring or dispersing through xeric habitats that predominates in Caatinga.